Sen. Rand Paul (R-Kentucky) criticized Democratic presidential front-runner Hillary Clinton's "shoot first" foreign policy stances in a new op-ed about the rise of the jihadist group Islamic State published Wednesday night.

Clinton argued earlier this month that President Barack Obama should have been more aggressive in arming moderate forces in Syria as a counter to Islamic State, also known as ISIS. Paul wrote in the Wall Street Journal that the U.S. was "lucky" that Obama disagreed with Clinton.

"To interventionists like former Secretary of State Hillary Clinton, we would caution that arming the Islamic rebels in Syria created a haven for the Islamic State. We are lucky Mrs. Clinton didn't get her way and the Obama administration did not bring about regime change in Syria. That new regime might well be ISIS," Paul wrote. "Those who say we should have done more to arm the Syrian rebel groups have it backward. Mrs. Clinton was also eager to shoot first in Syria before asking some important questions."

Paul has been staking out unorthodox policy positions for a candidate mulling an entry into a Republican presidential primary. Obama's recent air strikes against the Islamic State have had bipartisan support, but Paul said he had "mixed feelings" about them. Last week he dared Democrats to nominate a "war hawk" like Clinton.

In his op-ed, Paul argued much more caution is needed before the U.S. military is deployed overseas.

"The Islamic State represents a threat that should be taken seriously," he wrote. "But we should also recall how recent foreign-policy decisions have helped these extremists so that we don't make the same mistake of potentially aiding our enemies again."